Apparatus for flowing wells



Jan. 7,` 1941.

H. T. noRToN APPARATUS FOR FLOWING WELLS Filed May 8, 1939 2sheets-sheet 1` ln/vendor,

43;. vlinnn/e311 arfom.

Jan. 7, 1941. H. T. DoRToN APPARATUS FOR FLOWING WELLS Filed May 8A,1939 2 Sheets-Sheet 2 Hafvcy l' Dorfnia.

@ @mmMa/m Je@ atented Jan. 7., 1941 llllarvey "lll. Morton, li/fartha,y..

application li/liay d, ibid, serial ltTo. 2272503 i5 iUllaims. (mildd-2i 'llhis invention relates tothe control of fluid flow in gas andoil wells, and more particularly to methods and apparatus forcontrolling the injection of gas or other fluid into an oil producingsand for the purpose of artificially stimulating the recovery of oiltherefrom, and for controlling the flow ot gas or oil from a producingwell whenever it is desired to operate the well at less than its maximumcapacity.

lin repressuring oil producing sands by the injection of gas from apressure well, it has been found that the permeability of the sandvaries greatly at different points in the same pool, as well as indifferent strata, and that a materially different pressure may berequired for the injection of the desired volume of gas into onepressure well or stratum than is required for another. inasmuch as itwould not be economical to maintain a series of gas compressors orreser-l voirs discharging at different pressures into a multitude oi'pipe lines connecting to all of the pressure wells in any one field, lthas heretofore been the practice to control the pressure of the gasinjected by the use of pressure reducing restrictions in the pipe linesat each well.

it has been found, however, that when such restrictions are installed atthe well heads, it is practically impossible to maintain a continuousflow of gas into a well when the atmospheric temperature is at or nearfreezing, without the application of heat in some form, because theexpansion of the gas in passing through a flow restricting oriiicereduces its temperature to a point where any liquid entrained in the gasor otherwise present at the orifice quiclrly freezes and clogs thelatter. To avoid this difficulty, it has been proposed to install suchrestrictions in the well tubing at points sufficiently far below thesurface of the ground to insure that the temperature of the expanded gasremains above freezing. The difficulty with this arrangement, however,is that whenever it becomes necessary to change the size of arestricting orificeand this is a more or less frequent occurrencebecause of the continually changing conditions in the sand during Welloperation-either the entire tubing string must be removed from the wellto enable replacement of the orifice fitting, or the latter must beelevated inside the tubing and another fitting lowered into place by theuse of suitable tools. Both of these proce-dures are time consuming andoccasion the loss of substantial quantities of gas because of thenecessity `for blowing down the Well each time that the orifice httingis changed.

ll/liuch the same situation as that described above has also existed inconnection with edorts to restrictively control the 'flow of gas from aproducing well, and substantially the same defects are inherent in themethods and means that have been previously employed for this purpose.Somewhat similar problems are involved in restricting the production ofan oil well, be cause of the desirability from the standpoint ofefficiency of locating the flow restricting means at or near the face ofthe producing sand.

lit is therefore one of the objects of the present invention to providenew and improved pro-l cedures and apparatus for controlling the flow ofiiuids in gas and oil wells which will overcome the diiiiculties andremedy the detects heretofore encountered and existing in the methodsand. means previously available to the art for attainlng the sameultimate results.

another object is to provide novel and simplii'led means for restrictingthe flow of fluid into or out of a gas or oil well at points locatedsubstantial distances below the surface of the ground, and for readilyvarying from the well head the restrictive elfect of such means.

d. further object is to provide a new method for varying the size of aflow restricting orihce lin the tubing string of a pressure or producingwell which does not reduire either the use of tools for placing andremoving the orince iitting or the removal of the 'tubing string fromthe well.

Still another object is to provide a device for controlling the flow offluid upwardly or downwardly in the tubing of a gas or oil well whichcan be quickly and easily positioned at and removed from a point farbelow. the well head by gravity and fluid pressure alone. n

d still further object is to provide a novel method and apparatus of thecharacter described which are capable oi effecting substantial savingsiu the cost of oil and gas well operations wherein it is necessary torestrictively control the flow of fluid to or from the well.

These and other objects will appear more fully upon a consideration ofthe detailedldescription of the embodiments of the invention whichfollows. although three specific forms of apparatus embodying thepresent invention are described and illustrated in the accompanyingdrawings, it is to be expressly understood that these drawings are forthe purpose of illustration only and are not to be construed as definingthe limits of the invention, reference being had for this latter purposeto the appended claims.

Referring now to the drawings, wherein like reference charactersindicate like parts throughout the several views:

Fig. 1 is a vertical section, with certain elements shown in full andothers broken away in the interest of clarity, of one arrangement ofapparatus embodying the present invention adapted for controlling theflow of gas or other fluid into a pressure well for the purpose ofartificially stimulating the recovery of oil from producing wells in thesame field by injecting fluid under pressure into the oil producingsand;

Fig. 2 is a vertical sectional view, similar to Fig. 1, of a secondembodiment of the invention especially adapted for use in an oil or gasproducing well;

Fig. 3 is a vertical sectional view of a modification of the embodimentshown in Fig. 2; and

Figs. 4, 5 and 6 are fragmentary vertical sections, on an enlargedscale, of the flow restricting orifice fittings of Figs. l, 2 and 3,respectively.

In each of the three embodimei ts of the invention illustrated, theapparatus disclosed is adapted to restrictively control the flow of afluid into or out of a string of tubing through an orifice located asufficient distance below the surface of the ground to insure againstthe existence of freezing temperatures at the orifice, and includes anelement, hereinafter referred to as an orifice Plug, which determinesthe size of the flow restricting orifice and is capable of being loweredto and raised from the point of control by means of gravity and fluidpressure alone. In each instance, the lower end of the tubing string inwhich the restriction is required is provided with a fitting forming aseat for the orifice plug and embodying an orifice of fixed maximumsize, the effective size of which is varied by the orifice plug, whilethe upper end of the well tubing is provided with a suitable arrangementof valves, pipe connections and other means by which the orice plug maybe raised from and lowered to its seat without the use of fishing orother tools.

Referring now more particularly to the embodiment illustrated in Figs. 1and 4, there is 'indicated therein a pressure well containing a mainstring of tubing I2 which is adapted to extend downwardly to the stratuminto which the repressuring fluid is to be injected, and a secondarypipe or tubing string I3, in this in stance located inside of maintubing string I2, by means of which the fluid is delivered to the mainstring I2 at a predetermined reduced pressure.

To this end, the lower end of secondary tubing string I3 has threadedthereto a fitting |4 having an orifice I5 in its bottom and a taperedseat I6 leading to said orifice. The orifice I5 is of such size that,when unrestricted, it will pass fluid from the interior of tubing stringI3 to main.

string I2 at the maximum pressure which it might be desired to injectinto the well. In order to insure against clogging due to freezing, thefitting I4 is preferably located at least one hundred feet below theground level at the well head, although, of course, the exact locationof this fitting in any particular well may be selected to suit operatingconditions.

In order to suitably restrict the flow through orifice I5 of the gas orother fluid used for injection, an orifice plug I'I is removablyassociated with the tapered seat I6, the orifice plug of the embodimentillustrated being generally cylindrical in form and having its bottomend tapered as indicated at I8 to make a tight fit with tapered seat I6and a vertical bore |9 of restricted diameter extending therethrough,the size of the bore I9 being properly proportioned to pass fluid at thedesired rate and with the desired amount of expansion. It should also benoted that the bore I9 is of smaller diameter than orifice I5, acondition which ls essential t0 the operativeness of the method andapparatus of the present invention when apertured plugs are employed.'I'he upper end of plug l1 is also preferably rounded or tapered asindicated at 20 so that the plug will pass freely upwardly throughtubing string |3 without hanging when elevated in the manner later to bedescribed. As will be seen best from Fig. 4, orifice plug is maintainedin engagement with seat I6 by gravity and fluid pressure alone, thetapered surfaces of the plug and seat being accurately ground and formedof non-corrosive materials so as to insure at all times a tight, butnon-sticking, joint between these two elements.

At the well head the two strings of tubing I2 and I3 are connectedtogether for support, and t0 a control pipe 2| which communicates withthe interior of secondary tubing string I3, by means of a specialcoupling 22. As shown in Fig. 1, this coupling comprises a flange 23suitably secured to the upper endof main tubing string I2, a nipple 24into which the upper end of secondary string I3 is threaded and which isprovided with a flange 25 of smaller diameter than flange 23, anotherflange 26 complementary to flange 23 suitably secured to the lower endof control pipe 2|, and a pair of gaskets 2'I, the flange 25 of nipple24 being clamped between flanges 23 and 26, with the gaskets 21intervening, by means of bolts 28. With this form of coupling, thesecondary tubing string I3 does not have to be turned and can be runinside the mainI string I2 without the risk of lapping them together insetting up the pipe at the surface. Since the main tubing string I2 issealed at the top by the coupling 22, it may be provided, if desired,with a take-off line 29 just below the coupling and a valve 30 of anysuitable construction for controlling the flow in said line. When theapparatus shown in Fig. l is used for pressure well operation, it willbe understood that valve 30 is normally closed so as to prevent theescape of the repressuring fluid at the top of the main tubing string.

In order to attain the desired objective of raising and lowering theorifice plug I'I from the well head without the use of tools, controlpipe 2| is provided with a novel arrangement of valves and otherconnections which are capable of manipulation in such manner that theorifice plug can be dropped downwardly to its seat I6 through secondarytubing string I3 by gravity and elevated therefrom by the pressure ofthe fluid in the well.

In the embodiment illustrated, there is connected to control pipe 2| aninlet line 3| leading to any suitable source of relatively high pressureinjection fluid, such as a compressor or reservoir (not shown), the flowof iiuid from said source into control pipe 2| being controlled lby asuitable valve 32. It will be understood thatthe pressure of the fluidin inlet line' 3| is the maximum that would ever be required foroperation of the well, and that this pressure is reduced as required bypassing the fluid through the restricted bore I9 of an orifice plug I1.In order that the desired pressure reduction may be obtained for anyparticular operating condition, a plurality of oriiice plugs areprovided for use with each installation, these plugs being identical inconstruction except that the restricted bores thereof are made oidifferent diameters so as to provide different degrees of resistance tothe flow of fluid fj therethrough.

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.through secondary tubing string reaches oriiice plug il'.

Control pipe ll is also provided with a pair of gate valves and it,valve 33 being located between coupling il and inlet line tl, whilevalve is positioned at the upper end of the control pipe and serves toopen the latter to the atmosphere. The body oi upper or release valveill is suitably constructed at its outlet side to receive the threadedopen end oi a cushioning cage member it which is substantiallycylindrical in iorm, closed at its upper end, and provided with aplurality ci periorations wlrich permit the escape oi gas or other fluidfrom the interior thereof tothe atmosphere. rlhe inner diameters oi cagemember it and control pipe li are substantially the saine as that ofsecondary tubing string lin operating the apparatus just described forthe purpose oi injecting gas or other fluid into a stratum oi" oilproducing sand, and assuming that the parts are in the positionsindicated in l'lig. l.

with upper control or release valve closed, inlet valve and lowercontrol valve open, and taire-ofi valve lit closed, the repressuringiluid iiows iroin the compressor or reservoir at a relatively highpressure through inlet line into control pipe lli, and thence downwardlylll until it ,llt this point the resistance to iiow through oriiice llioi htting iii offered by the restricted bore ii oi the oriiice plugreduces the pressure oi? the iluid as it passes into main tubing stringil. to the proper amount desired ior the repressuring operation, theiluid leaving the htting iii continuing to liow downwardly through themain tubing string until it reaches the level where it passes into thesand. Due to the greater pressure exerted upon the euposeol area oi' theupper end of the orifice plug, a tight seal is maintained between theground tapered surfaces oi the lower end it ol the plug and seat itwhich prevents leakage through oriiice lli around the outside of theplug, without the necessity for using latching or other mechanical meansfor positively holding the plug in position.

lWhen it is desired to vary the pressure of the iiuid issuing :tromritting lll into the main tubing string, the oriiice plug il is@ raisedto the surface and replaced by one having a bore of different diameter.To effect this replacement in accordance with the present invention, itis only necessary to close inlet valve ill and then open upper controlor release valve lil, whereupon the pressure of the back flow oi gasfrom the well is exerted against the bottom end of orifice plug il and,in conjunction with the resistance to upward flow offered by therestricted bore ill, unseats the plug and forces it to the surface whereit is caught in cushioning cage it. Release valve it is then closed soas to permit the removal oi cushioning cage lil and the trapped orihceplug. A plug having a, bore of proper diameter to eiect the desiredchange in pressure may be substituted for the one removed by firstclosing lower control valve 33, then opening release valve lill, anddropping the replacing plug into the upper end of the control pipe Whereit comes to rest on the gate of lower control valve 33. Releasepossibility of injury to its tapered lower end it or the seat lli, thisvelocity may be reduced by manipulating release valve lll so as toproduce a 'counterfiow upwardly through the secondary tubing stringwhich will check the fall oi the oriiice plug and permit it to be seatedas lightly as desired. When the plug reaches its seat, release valve lilis tightly closed and the repressurlng operation continued by openinginlet valve In Figs. 2 and 5 there is disclosed another ernbodirnent oithe method and apparatus oi" the present invention which is particularlyadapted ior use in controlling the iiow oi gas or oil from a producingwell, but which embodies the same fundamental structure and mode oioperation as the embodiment oi l'ligs. l and Il. For simplicity, thefollowing description will be limited to the use of the invention inconnection with a gas a producing well, although it will be obvious thatthe same method and apparatus is equally well adapted to oil welloperation.

In the form illustrated, the main and secondary tubing strings lli andit and a control pipe ill are Fill connected together by a coupling insubstan tially the saine manner as that heretofore described inconnection with the nrst embodiment, and control pipe il is similarlyprovided with control valves and lili, inlet line iii and valve iii, andcushioning cage The upper end ot main tubing-string iii is also providedwith a taire-oii line lill and valve this line in the present embodimentconstituting the field line into which is delivered the gas recoveredfrom the well.

is shown, both strings of tubing preferably er:- tend downwardly' in thewell lll all the way into the shot hole in the producing stratum of thesand, the main tubing string il being provided with a suitable packer itsealing oil the upper portion oi the well from the space into whichflows the gas which it is desired to remove from the well. The lower endof main tubing string il is closed oii :troni direct communication withthe shot hole il by a cap llt, preferably detachably secured to thetubing as by a threaded connection. The lower end oi secondary tubingstring it is similarly connected to a fitting iii having an orifice lliand tapered seat it of substantially the san/reconstruction as theiitting ill sho-wn in Figs. l and li, but differing from the latter inthat it is also provided with an opening all in the side wall thereoflocated above the position occupied by the upper end of theoriiice plugil whenthe latter is in engagement with its seat it. The interior oifitting lll is in direct communication with the shot hole iii through anipple lli which passes through an opening lit in cap it and is threadedint-o the opening 1li' of fitting lll. The inside diameter of nipple lliis at least as great as that of orifice it.

Inl normal operation of this second embodiment of the invention for therecovery of gas from the well, all of control valves il, it and 3i areclosed, while take-off valve til and any other valves located in theline it are open, the ground pressure forcing the gas from the shot hole33 through the nipple t3, downwardly through the restricted bore l@ oforiiice plug ll and into ill iti

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the cap 40 and the lower end of main tubing string I2, whence it flowsupwardly through the latter into take-off line 29 which delivers it tostorage or any other desired destination. In passing through the bore ofthe orifice plug, the flow of the gas is restricted to an extentdepending upon the size of said bore, the latter being so selected as toresult in the desired rate of production by the well. As in the case ofthe embodiment of Figs. 1 and 4, orifice I5 of fitting 4| is of suchsize as, in the absence of an orifice plug, will enable operation of thewell at its maximum capacity.

When it is desired to change the size of orifice plug being used, it isnormally necessary only to open control valves 33 and 34, whereupon thepressure of the back flow of gas from main tubing string I2 is exertedagainst the bottom of the orifice plug and, because of the resistance toupward flow into the inner string of tubing offered by the restrictedbore of the plug, unseats the latter and forces it to the surface whereit is trapped in cushioning cage 35 in the manner previously described.

In view of the fact that, under certain conditions of well operation,the pressure of the back flow from the main tubing string is ineffectivet0 unseat the orifice plug and raise it tothe surface, additional meanshave been provided which may As shown, a suitable reservoir 45 isprovided at the Well head connected by piping 46 and valve 41 to a crossconnection 48 between take-ofi' or field line 29 and line 3| whichconnects to control pipe 2| at a point intermediate valves 33 and 34.Lines 29 and 3| are also provided with valves 49 and 50, respectively,on the field side ofcross connection 48. With this arrangement, thereservoir 45 may be filled with gas at substantially the same pressureas that existing at the bottom of the Well 31 either by opening valves41 and 30 with all other valves closed, in which event the gas from theshot hole 38 will follow the same path of flow as during normalproduction except that it will be diverted into the reservoir 45 insteadof continuing past valve 49 in the field line 29, or by opening lowercontrol valve 33 and valves 32 and 41 with all other valves closed,whereupon the gas will flow directly from the shot hole through nipple43 and upwardly through secondary tubing string I3 into the reservoir 45via line 3|, cross connection 48 and piping 46. Reservoir 45 may also besupplied with gas under pressure from any other suitable source, as by apipe 5| and valve 52.

I'he reservoir 45 being charged in any of the ways just described, if'the normal back flow from the main tubing string fails to unseat theorifice plug, the alternative or emergency procedure is to first blowdown the well pressure until the latter is below that of the gas in thereservoir, and then release the reservoir pressure into the main tubingstring by opening valves 41 and 30, valve 49 being closed, permittingthis pressure to blow into the atmosphere through tubing string I3 andcontrol pipe 2| in the same way as when the unseating operation isperformed in normal manner by the back fiow from the field line. Inblowing the well down preparatory to the use of reservoir pressure forunseating the orifice plug and bringing it to the surface,l wastage ofgas can be prevented by blowing either into the field line 29 throughline 3| and cross connection 48,

or into the continuation of line `3| beyond the cross connection.

After the orifice plug has been unseated and raised to the surface byeither the normal or emergency operation described, ,the replacingplugmay be dropped down onto its seat I6 in fitting 4| by gravity by thesame manipulation of valves as that described in connection with theembodiment of Figs. l and 4, taking care.

only that field line valve 30 is closed.

When conditions are such that it is not practical to run the secondarytubing string I3 inside of main string I2 in a producing well, thearrangement illustrated in Figs. 2 and 5 may be modified in the mannerindicated in Figs. 3 and 6, but without any change in the fundamentalprinciples involved. As shown in the latter two figures, the arrangementof the elements is substantially the same as that of Figs. 2 and 5except for the specific construction at the bottom of the well and thefact that the secondary tubing string I3 is located outside of maintubing string I2, a change Whichalso involves the replacement of thespecial coupling 22 by a blank sealing disk 53 closing the upper end ofthe main tubing string. In this connection, it should be noted that itis intended that the connections at the Well head to the emergencyreservoir 45, shown to the right of the line A-A in Fig. 2, should beduplicated in Fig. 3, if desired.

As is best illustrated in Fig. 6, the lower ends of both tubing stringsI2 and I3 are preferably threaded into a combined cap and orifice plugseat fitting 54, the portion of said fitting beneath the end ofsecondary tubing string- I3 being provided wth an orifice I5 and taperedseat I6 adapted to support an orifice plug I1, all as previouslydescribed, and the orifice I5 communicating with the interior of tubingstring I2 through a suitable passageway 55. Just above its point ofconnection to the fitting 54, and at a position terior of tubing stringI3 and shot hole 38.

Aside from these differences in structural detail, including themodification of packer 39 to adapt it for use with two strings of tubinginstead of one, the embodiment of Figs. 3 and 6 is of substantially thesame construction, and operates in accordance With the same method, asthe form of the invention shown in Figs. 2 and 5, previously describedin detail.

It will be apparent from the foregoing description that the presentinvention provides both a novel method and novel means for controllingthe fiow of fiuids in gas and oil wells which greatly facilitate welloperation and overcome the defects of the prior procedures andmechanisms heretofore used for varying the pressure or rate of flow ofgas, oil and other iiuids in pressure and producing wells. By thepresent invention it has been made possible'to quickly and easily changethe size of a flow restricting fitting normally positioned a substantialdistance below the surface of the ground, merely by the manipulation ofcertain valves at the well head and Without the necessity for usingfishing tools or like instrumentalities, or for withdrawing the tubingfrom the well in order to obtain access to the fitting. Not only do thenew method and apparatus effect substantial savings in time and labor,but there is also very little wastage of fluid in lill fill

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the operations involved. The importance of such savings will be readilyappreciated when it is considered that in repressuring operations, inparticular, it is necessary to vary the pressure of the iiuid which isinjected into the oil producing sand at relatively frequent intervals inorder to maintain the desired rate of recovery of the producing wells.rllhese and other features, all of which will be apparent from thedisclosure herein, endow the present invention with substantialadvantages over the methods and apparatus of the same generic characterhitherto known to the art.

dlthoughl three specific forms of apparatus embodying the invention havebeen described and illustrated in the accompanying drawings, it will beobvious that the invention is not limited to the particular structuresshown, but is capable of a variety of mechanical embodiments. Forexample, the fittings which are connected to the lower ends of thetubing strings may vary in their details of construction from thosespecifically illustrated in the drawings, and may be detachablyconnected to the tubing in other ways than by the threaded connectionsshown. It is also within the contemplation of the present invention thata plurality ofdiow restricting orifices may be employed at diderentlevels in the same well, and that the orifice plugs may be made solidinstead of with restricted bores, in which latter case the variation incontrol might be effected by varying the length ci the tapered lowerends of the plugs so as to expose more or less of the areas of oricesformed in the sides of the fittings in which the plugs are seated. Itshould also be understood that the particular arrangement of valves andconnections at the well head which` enable the orifice plug to be raisedby fluid pressure alone may be varied somewhat fromthe embodimentsillustrated. Various other changes, which will now suggest themselves tothose skilled in the art, may be made in the procedural steps of themethod, and in the form, details of construction and arrangements of theparts of the apparatus, without departing from the spirit of theinvention. Reference is therefore to be had to the appended claims for adefinition of the limits of the invention.

What is claimed is:

l. in gas or oil well apparatus of the character described, thecombination of a string of tubing through which fluid may be injectedinto or removed from the well, means connected to said tubing at a pointa substantial distance below the surface of the ground providing anoriflce through which fluid may pass from or to the interior of saidtubing, means including an orifice plug associated with said orifice forrestricting the flow of fluid through said orifice, said plug beingmaintained in flow restricting position solely by the force of gravityand the pressure of the fluid in said tubing thereabove, and means forproducing a flow of fluid into and upwardly through said tubing ofsufficient force to raise said plug 'from its flow restricting positionto the upper end of said tubing by fluid pressure alone.

2. in gas or oil well apparatus of the character described, thecombination of a string of tubing through which fluid may be injectedinto or. re-

moved from the well, means connected to said tubing at a point asubstantial distance below the surface of the ground providing anorifice through which iiuid may pass from or tothe interior of saidtubing. a tapered seat associated with said orifice, an oriflce plughaving a tapered lower end adapted to engage said seat and a restrictedbore therethrough of smaller diameter than said orice for controllingthe flow 0f fluid through said orifice, said plug being malntained in owrestricting position on said seat solely by the force of gravity and thepressin'e of the fluid in said tubing thereabove, and means forproducing a now of fluid into and upwardly through said tubing ofsufficient force to unseat said plug and raise it to the upper end ofsaid tubing by fluid pressure alone.

3. In gas or oil well apparatus of the character described, thecombination of a string of tubing through which iiuid may be injectedinto or removed from the well, means connected to said tubing at a pointa substantial distance below the surface of the ground providing anorifice through which iiuid may pass from or to the interior of saidtubing, means including an orifice plug associated with said orifice forrestricting the flow of huid through said orifice, said plug beingmaintained in iiow restricting position solely by the force of gravityand the pressure of the Huid in said tubing thereabove, means forproducing a flow of fluid into and upwardly through said tubing ofsumcient force to raise said plug from its flow restricting position tothe upper end of said tubing by fluid pressure alone, and means fortrapping said plug at the upper end of said tubing while permitting theescape of said fluid therefrom.

i. In gas or oil well apparatus of the character described, thecombination of a string of tubing through which fluid may be injectedinto or removed from the well, means connected to said tubing at a pointa substantial distance below the surface of the ground providing anoridce through which fluid may pass from or to the interior of saidtubing, means including an orifice plug associated with said orifice forrestricting the How of huid through said orifice, said plug beingmaintained in flow restricting position solely by the force of gravityand the pressure of the fluid 'in said tubing thereabove, means forproducing a now of duid into and upwardly through said tubing ofsumcient force to raise said plug from its how restricting position tothe upper end of said tubing by huid pressure alone, and a perforatedcage member detachably connected to the upper end of said tubing fortrapping said plug while permitting the escape of said fluid therefrom.

5. ln gas or oil well apparatus of the character described, thecombination of a string of tubing through which fluid may be injectedinto or removed from the well, means connected to said tubing at a pointa substantial distance below the surface of the ground providing anorifice through which fluid may pass from or to the interior of saidtubing, means including an orifice plug associated with said orifice forrestricting the iiow of fluid through said orifice, said plug beingmaintained in flow restricting position solely by the force of gravityand the pressure of the fluid in said tubing thereabove, means forproducing a flow of iiuid into and upwardly through said tubing ofsulicient force to raise said plug from its flow restricting position tothe upper end of said tubing by uid pressure alone, including a releasevalve at the upper end of said tubing for opening the latter to theatmosphere, and means detachably connected to the discharge side of saidvalve for trapping said plug while permitting the escape of saidiiuidfrom said tubing.

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6. In gas or oil well apparatus` of the character described, thecombination of a string of tubing through which fluid may be injectedinto or removed from the well, means connected to said tubing at a pointa substantial distance below the surface of the ground providing anorifice through which fluid may pass from or to the interior of saidtubing, means including an orifice plug associated with said orifice forrestricting the flow of fluid through said orifice, said plug beingmaintained in flow restricting position solely by .the force of gravityand the pressure of the fluid in said tubing thereabove, and means forproducing a flow of fluid into and upwardly through said tubing ofsufficient force to raise said plug from its flow vrestricting positionto the upper end of said tubing by fluid pressure alone, including apair of valves in said tubing at the upper end thereof for opening thelatter to the atmosphere, the section of .tubing intermediate saidvalves comprising a pressure equalizing chamber for reception of saidplug preparatory to dropping the same through said tubing by gravity toflow restricting position.

7, In gas or oil well apparatus of the character described, thecombination of-a string of tubing through which'fiuid may be injectedinto or removed from the well, a fitting connected to said tubing havingan orifice through which fluid may pass from or to the 'interior of saidtubing and a tapered seat leading toward said orifice, and asubstantially cylindrical orifice plug having a tapered lower endadapted to engage said seat and a vertical axial bore therethrough ofsmaller diameter than said orifice for vrestrictively controlling theflow of fluid through the latter, said plug being maintained in flowrestricting position on said seat solely by the force of gravity and thepressure of the fluid in said tubing thereabove.

8. In gas or oil well apparatus of the character described, thecombination of a main string of tubing through which fluid may beinjected into or removed from the well, a secondary tubing stringassociated with said main string, means connected to said secondarystring at a point a substantial distance below the well head providingan orifice through which fluid may pass between the interiors of saidmain and secondary strings, means for restricting the flow of fluidthrough said orifice including an oriflce plug maintained in flowrestricting position solely by the force of gravity and the pressure ofthe fluid in said secondary string, and means for producing a flow offluid into and upwardly through said secondary string of sufficientforce to raise said plug from its flow restricting position to the wellhead by fluid pressure alone.

9. In gas or oil well apparatus of the character described, thecombination of a main string of string associated with said main string,means connected to said secondary string at a point a substantialdistance below the well head providing an orifice through which fluidmay pass between the interiors of said main and secondary strings, meansfor restricting the flow of fluid through said orifice including anorifice plug maintained in flow restricting position-so1ely by the forceof gravity and the pressure of the fluid in said secondary string, meansfor producing a flow of fluid into and upwardly through said secondarystring of suicient force to raise said plug from its flow restrictingposition to the well head by uid pressure alone, including valve meansfor opening said secondary string to the atmosphere, and means fortrapping said plug at the upper end of said secondary string whilepermitting the escape therefrom of said fluid.

10. In a pressure well, the combination of a main string of tubingthrough which a repressuring fluid'may be injected into the well. asecondary tubing string associated with said main string, a connectionto the upper end of said secondary string for supplying repressuringfluid thereto, a fitting connected to said secondary string at a point asubstantial distance below the well head having an orifice through whichthe repressuring fluid may flow from said secondary string into saidmain string, means for restricting the flow of fluid through saidorifice including a removable plug maintained in flow restrictingposition solely by the force of gravity and the pressure of the fluid insaid secondary string, and means for producing a back flow of fluid fromsaid main string into and upwardly through said secondary string ofsuiiicient force to raise said plug from its flow restricting positionto the well head by fluid pressure alone, including 'valve means fordisconnecting said secondary string from the source of repressuringfluid and for opening said string to the atmosphere.

11. In a pressure well, the combination of a main string of tubingthrough which a repressuring fluid may be injected into the well, asecondary tubing string asssociated with said main string, a connectionto the upper end of said secondary string for supplying repressuringfluid thereto, a fitting connected to said secondary string at a point asubstantial distance below the well head having an orifice through which`the repressuring fluid may flow from said secincluding a removable plugmaintained in flow restricting position solely by the force of gravityand the pressure of the fluid in said secondary string, and means forproducing a back flow of fluid from said main string into and upwardlythrough said secondary string of sufficient force to raise said plugfrom 'its flow restricting position to the well head by fluid pressurealone, including a valve for disconnecting said secondary string fromthe source of repressuring fluid, a second valve in said secondarystring above said connection for opening said string to the atmosphere,and a third valve in said secondary string below said connection, thesection of said secondary string intermediate said second and thirdvalves comprising a pressure equalizing chamber for reception of saidplug preparatory to dropping the same through said secondary string bygravity to flow restricting position.

12. In a pressure well, the combination of a main string of tubingthrough which a repressuring fluid may be injected into the well, asecondary tubing string associated with said main string, a connectionto the upper end of said secondary string for supplying repressuringfluid thereto, a fitting connected to said secondary string at a point asubstantial distance below the well head having an orifice through whichthe repressuring fluid may flow from said secondary string into saidmain string, a tapered seat leading toward said orifice, an orifice plughaving a tapered lower end adapted to engage said seat and a restrictedbore therethrough of a diameter less than that of said orifice forcontrolling the flow of fluid through the latter, said plug beingassauts 7 maintained in flow restricting position on said seat solely bythe force o! gravity and the pressure or the fluid in said secondarystring, and ineens tor producing a back iiow oi.' iiuid from the mainstring into and upwardly through said seeondary string of sumcient forceto unseat said plug and raise it to the well head by iluid pressurealone. v 13. In a. producing well, the combination oi a id main stringof tubing through which the iluid to he recovered from the well may beraised to the welt head, said string being sealed against directcommunication with the well, a secondary tubing string associated withsaid main string and havw ing an opening in the wali thereof throughwhich nuid may ilow from the weli, means providing communication betweenthe interiors oi said main and secondary strings, including an orificelocated below the level of said opening 2d in the secondary string.means including a removable orifice plug associated with said oriiicefor restricting the flow of huid through the lat ter. and means forproducing a back ilow of fluid downwardly through said main string,through 25 said oriiice and upwardly into and through said secondarystring of sufdcient torce to raise said plug irom'its flow restrictingposition to the top oi said secondary string by fluid pressure alone.14. In a producing well. the combination of a 3d main string of tubingthrough which the tiuid to be recovered from the well may be raised tothe well head, said string being sealed against direct communicationwith the well. a secondary tubing string associated with said mainstring and 35 having an opening in the wall thereof through which fluidmay tlow from the well, means providing communication between theinferiores! said main and secondary strings, includingan oriiice locatedbelow the level oi said opening in' M the secondary string, meansincluding'a remov able` oridce plug' associated with said orice forrestricting the i'low of iluid through the latter. and means forproducing a back flow of iluld downwardly through said main string,through said oriiice and upwardly into and through said u secondarystring of sufilcient force t raise said plug from its now restrictingposition to the top oi said secondary string by iluid pressure alone.said last named means including a reservoir, means for charging saidreservoir with uid from l0 said well. means for connecting saidreservoir to said main string, and valve means for opening saidsecondary string to the atmosphere.,

15. In a producing well, the combination oi a main string of tubingthrough which the iiuid to 18 be recovered from the well may be raisedto the well head. said string being sealed against direct communicationwith the well. a secondary tubing string associated with said mainstring and hav- 4 ing an opening in the wall thereof through which 20fluid may iiow from the well, means providing communication between theinteriors oi.' said main and secondary strings. including an oriiicelocated below the level o! said opening in the secondary string and atapered seat leading toward said orifice, a removable orifice plughaving a tapered lower end adapted to engage said seat and a restrictedbore therethrough of a diameter less than that or said orifice forcontrolling the now of iiuid through the latter. said plug beingmaintained in iiow restricting position on said seat solely by the forceo! gravity and the pressure of the iiuid in said secondary string, and'means for producing a back iiow of iiuid downwardly through said mainstring, through said oriilce and upwardly into and through saidsecondary string of suicient force to unseat said plug and raise it tothe top of said secondary string by huid pressure alone..

HARVEY T. DORTON. 40

